The Geological Hazards Sensitivity Evaluation Based On Weighted Information Method

With many ravines and broken terrain,Chinese Loess Plateau is one of the places wheregeological disasters occur at a high incidence. Especially, slope disasters, such as landslidesand avalanche, cause a large number of casualties and property losses.Distribution of thesedisasters has a characteristic of basin, and this paper focused on Yan River Basin, whichcovers Ansai Country, Baota region, Zhidan Country, Yanchang Country.On the basis ofdetailed geological disaster investigation map(1:50000) of the area, comprehensive dataabout the geological environment and geological hazards were collected. And with the helpof GIS software, it analyzed the hazard types, distribution, development conditions andfactors and made zoning evaluation according to the liability. Main work of this paper is asthe following:（1）With the functions of data acquisition in MapGIS and data processing in ArcGIS,a geological hazard spatial database was established, including geographic data, basicgeological data,location data of disasters and raster data.（2）Statistical study was conducted about the disaster types of the area. Analysis ofthe relationship between hazard distribution and water system in terms of the valley locationand development period reveal the hazard distribution characteristics of the area. Thenumber of geological hazards is in all957, including landslide, avalanche, and unstableslopes. The dominant type is landslide, whose number is as large as658, making up68.7%.Unstable slope just follows landslide,167, making up17.5%. Avalanche is the least, only132, making up13.8%. geological disaster distributes densely in area with many humanactivities such as senile valley, midstream region, urban.（3）Factors that contribute to the development of geological disaster can be dividedinto controlling factors and triggering factors according to internal and external causes.Controlling factor includestratum structure,topography, valley topography, groundwater.Triggering factors include rainfall infiltration, river erosion, reservoir storage,andhumanengineering activities. Because geological environment changes slowly, rainfall and humanactivity are the most active factors, to induce geological disaster.（4）After analyzing the advantages and disadvantages ofAHP and information law in their application to geological disaster-prone zoning assessment, it put up with an improvedweighted information method by employing the weights of factors obtained from AHP inthe information method. Therefore is a combination of the two methodologies above.Thenaccording to the factors like slope ratio, slope type, vegetation, river valley landforms,stratigraphy, rainfall, road distance, residential position, the improved method were utilizedto make geology division according to disaster liability. Results show that the acreage ofhigh-prone area is1664.96km2, accounting for19.24%of the study area.The middle pronearea is3102.02km2, accounting for35.83%. And the low-prone area is3888.99km2,accounting for44.92%.